1. Field of the Invention
The present invention relates to a resist pattern forming apparatus and a resist pattern forming method for forming a resist pattern on a substrate such as a semiconductor wafer and a LCD substrate (a glass substrate for a liquid crystal display) and developing the substrate after coating therewith, for example, a resist solution, and exposure.
2. Description of the Related Art
In a semiconductor apparatus fabrication process, photolithography technology is used. In photolithography technology, a resist solution is coated on a substrate such as a semiconductor wafer (hereinafter referred to as a wafer). With a photo mask, the resist film is exposed and developed. As a result, a desired resist pattern is formed on the substrate.
The photolithography technology is performed by a pattern forming system in which an aligner is connected to a coating and developing apparatus. For example, when the wafer is processed, the coating and developing apparatus is composed of a cassette stage, a transfer mechanism, a processing station and an interface station. The carrier stage loads and unloads a wafer carrier. The transfer mechanism conveys a wafer from a carrier placed on the carrier stage. The coating and developing apparatus is connected to the aligner.
The wafer is carried into a processing station with a wafer transfer mechanism. A resist film is formed thereon in a coating unit, after that the wafer is exposed in an aligner. The wafer is then brought back to the processing station, and a developing process is performed in a developing unit and the wafer is thereafter returned to the cassette with the transfer mechanism. The wafer is next transferred to an etching apparatus where the etching process is performed.
Incidentally, the processing state of the resist film thickness, the exposing process, the developing process, and the etching process may not meet a target value because of a fluctuation in temperature and humidity and the like, and factors such as the condition of the surface of the wafer and atmospheric pressure, even when the process is performed under constant processing conditions.
Thus, conventionally, a substrate is pulled out, for example, every time a fixed number of the substrates are processed. The substrate is conveyed to an inspection unit disposed in an area separated from the coating and developing apparatus. In the inspection unit, inspection is performed on items such as, a thickness of the resist film formed on the wafer after the coating of the resist solution, a line width of a resist pattern after the developing process, an accuracy that a base pattern matches with the resist pattern, inconsistency on the developed surface, a defect on the development, a line width of an etched line after the etching and a defect on the surface after the etching process. A decision is made whether the processing condition of each portion is appropriate based on the inspection result. The processing state of the wafer that is sent to a manufacturing line is amended to approach the target value based on the decision.
However, since there is no standard value that determines the amendment, an augmenter of an amending operation of such processing condition is determined by the experience of an operator and the like obtained via trial and error. In addition, there is a plurality of parameters that are objects of the amendment. The operation is troublesome since the inspection has to be repeated many times with various processing conditions and amendment values. In addition, the operation becomes difficult to perform in the absence of an experienced operator.
Furthermore, conventionally, the amendment of the processing conditions is performed with each of the plurality of units, the coating unit, the developing unit, the aligner, and the etching apparatus. Thus, the operator has to visit each of those units or apparatuses in order to amend the processing conditions thereof, which also causes the operation to be troublesome from this point of view.